Merge "Update HACKING.rst per recent changes"

2 files changed, 11 insertions, 4 deletions

diff --git a/HACKING.rst b/HACKING.rst
index 3f6a3ed..3cea316 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -26,16 +26,23 @@ General
 
     mylist = Foo().list() # OKAY, does not shadow built-in
 
+- Use the "is not" operator when testing for unequal identities. Example::
 
-- Use the "not in" operator for collection membership evaluation. Example::
+    if not X is Y:  # BAD, intended behavior is ambiguous
+        pass
+
+    if X is not Y:  # OKAY, intuitive
+        pass
+
+- Use the "not in" operator for evaluating membership in a collection. Example::
 
-    if not X in Y:  # BAD, hard to understand
+    if not X in Y:  # BAD, intended behavior is ambiguous
         pass
 
     if X not in Y:  # OKAY, intuitive
         pass
 
-    if not (X in Y or X is Z):  # OKAY, still better than all those 'not's
+    if not (X in Y or X in Z):  # OKAY, still better than all those 'not's
         pass
 
 
diff --git a/openstack/common/scheduler/filters/json_filter.py b/openstack/common/scheduler/filters/json_filter.py
index 273d55e..9118bc2 100644
--- a/openstack/common/scheduler/filters/json_filter.py
+++ b/openstack/common/scheduler/filters/json_filter.py
@@ -32,7 +32,7 @@ class JsonFilter(filters.BaseHostFilter):
         if len(args) < 2:
             return False
         if op is operator.contains:
-            bad = not args[0] in args[1:]
+            bad = args[0] not in args[1:]
         else:
             bad = [arg for arg in args[1:]
                    if not op(args[0], arg)]